Electronic microscope



1942. H. SCHUCHMANN ErA &

ELECTRONIC MI CROSCOPE 2 Sheets-Sheet 1 Filed Feb. 28, 1940 &mm

1942. SCHUCHMANN ET'AL 2,305,459

ELEGTRONIG MICROSCOPE Filed Feb. 28 1940 2 Sheets-Sheet 2 f/gw? 67 32.53 gg Hana (Binin mm J" Patented Dec. 15, 1942 ELECTRONIC MICROSCOPEHans Schuchmann and Bodo von Borries, Berlin- Spandau, and Helmut Ruska,Berlin-Nikolassee, Germany; vested in the Alien Property CustodianApplication February 28, 1940, Serial No. &21,238 In Germany November11, 1938 6 Claims.

This invention relates to improvements in electronic microscopes.

As is well known, electronic microscopes consist`of a large number ofindividual parts which support, for instance, the electron producingdevice, the condenser lens, the sluicing device, the magniiying lensesand the like. These individual parts must be assembled to form apressure-tight vessel. To seal the individual parts with respect to oneanother, it is common practice to provide the parts at the points wherethey are assembled with ground scaling cones engaging one another in acorresponding manner. The cones ensure a sufficient tightress even whenin operation for a number of years, so that it is possible to maintainthe vacuum necessary for Operating the electronic microscope. Thedisengagement of these scaling cones, which is occasionally necessaryfor replacing coils or the like, encountered hitherto greatdifiiculties, since these cones, particularly when in operation for avery long period, are in a jammed state. In the types hitherto known itmay therefore happen that the cones When being brought out of engagementbecome damaged so that the particular part of the electronic microscopecan no longer perform its proper function.

The object of the present invention is to remove the above drawbacks ina simple manner.

To this end, the invention provides adjacent parts of the microscopevessel, engaging each other with the aid of a scaling cone structure,with a screw nut seated on a threaded portion of one of the two parts soas to exert, when screwed in the proper direction, a force against theother part tending to disengage the sealing cone from its conical seat.By means of these screws it is possible to disengage the individualparts in a simple manner and without damaging the same, since the screwspernit exerting a concentric pressure on the cone to be removed.

Another object of the invention consists in the improvement of theadjusting devices for the electronic microscope and in simpliiying theoperation of the apparatus. ccording to the invention, adjustingdevices, such as adjusting screws, eccentric Controls or the likelocated at a certain distance from the place of the observer, areextended to a point which is easily accessible for the observer andprovided at this point with knobs or handles. This feature of theinvention renders it possible to adjust the individual parts of theelectronic microscope in an exact manner without the observer having toleave his seat. The arrangement is preferably so designed that besidesthese knobs for adjusting the screws or the like, easily accessible fromthe seat of the observer, further knobs to be less frequently actuatedare arranged in the neighborhood of the aforementioned nuts or threads,i. e. at a certain distance from the seat of the observer.

The invention may be carried into practice in various ways, as will beapparent from the following description of the embodiment shown in thedrawings in which Figs. 1 and 2 illustrate by sectional views the upperand the lower portion, respectively, of an electronic microscopeconsisting of various individual parts provided with sealing cones.

In the drawings, l denotes the holder for the electron producing deviceof the electronic microscope The electron beam issuing from this devicepasses through the magnetic field of a condensing lens ll (Fig. 1)before it impinges upon the object whose magnified image is to beproduced. The object is located in the chamber 52 of a sluicing device2:1 (Fig. 2). Thence the beam, modified in accordance with theelectronoptical teXture of the object, passes through the lens field ofan objective coil 55 which p roduces an intermediate image, invisible ormade visible by fiuorescent means, in the interior of an intermediatevesscl section 29, whence the beam reaches the lens field of aprojection coil throwing an enlarged image onto a luminescent screendisposed in the base section 45 of the instrument.

The holder l oi the electron source is provided at its upper end with acone 2 which ts a corresponding cone 3 of an insulating body 4 formingthe uppermost section of the microscope vessel. To disengage these twocones a nut 5 is provided which is screwed in the upper end 6 of theholder I, provided with a corresponding thread. To disengage the conethe nut 5 is turned in the downward direction and presses against theuppcr edge 'l of the insulating body.

The insulating body itself has at its lower end a scaling cone 8 whichis in engagement with a correspondingly shaped part 9 of theintermediate piece I@ iorming a second section of the microscope vessel,inspection windows II and 2 being secured to the piece !il forinspecting the operation of the electron producing device. To disengagethe cones 8 and e, a nut !3 is provided which is screwed on acorresponding outer thread provided in the upper part of theintermediate piece I il. When assembling the parts 4 and IU, the nut !3is screwed on part IO, after which a pressure ring I i is placed on thenut.

When the cones 8 and 9 have been brought into engagement with eachother, the pressure ring !4 i firmly secured in this position to thebody 4 by a binding agent, as indicated at !5. In this manner the nut |3serving to disengage the cones when separating parts 4 and n from eachother engages the pressure piece l4 in a uniform manner, thus exerting auniform concentrical pressure on the body 4.

l6 denotes a third section of the vacuum wall of the electronicmicroscope. This section is tightly joined with part II] and surroundedby the oondenser coil ll. The piece IB has at its lower end a cone !8 inengagenent with a correspondingly shaped part [9 of the body of theobject sluice 20, the latter forming the fourth consecutive section ofthe vessel structure. The cone !8 is firmly pressed against the cone !9with the aid of the pressure nut 2. This nut is screwed into the upperend of the sluice body provided with an inner thread 22 and also servesto disengage, if necessary, the two cones. To this end, a nut 23 is inengagement with the cone B and is secured against rotation by means of aset screw 24. To disengage the cones the nut Zi is turned so as to movein the upward direction and its inner, fiange-shaped portion 25 ispressed against the lower side of the correspondingly designed nut 23.

26 denotes another section of the structure.

This section carries the objective coil 55 and has at its lower end asealing cone 2': fitting in the scaling cone 28 of a sixth section 29 ofthe vacuum wall. The cones 27 and 28 are disengaged by the nut 30 whichis screwed on the thread 3| of the objective coil body 26 beforebringing the cones into engagement With each other. To separate orloosen the cones, the nut 311 is turned so as to move in the downwarddirection and thus is pressed against the upper end 32 of the cone 28.33 and 34 denote inspection windows inserted in an enlarged portion 12of section 29. Through windows 33 an intermediate image produced by theprojection coil may be directly Viewed by the observer when he stands,While a prism 35 permits an indirect observation through each window 34when the -observer is seated. 36 designates a further vessel sectionwhich forms the body of the projection coil 80 and has a sealing cone 31which engages a corresponding scaling cone 38 of the part 29. To bringthe two cones out of engagement with one another, use is made of a nut39 which when turned so as to move in the upward direction pressesagainst the edge 40 thus disengaging the cones.

In a similar manner the lower cone 4l of the projection coil body 35 isbrought out of engagement with the cone 42 by means of the nut 43. Thecone 42 is integral with the lower part 45 of the electronic microscopeprovided with inspection windows 44 and secured by screws to the basesection 46 serving for the reception of the fluorescent screen.

The body 20 of the sluicing device for introducing the object into thevacuum chamber has a lateral bore 52 (Fig. 2) for receiving a cock plug(not shown) whose cross bore serves to accommodate the object to betested. 53 is a lateral opening in the sluice body 20 for introducingthe object into the cross bore of the cock plug. After such insertionthe plug is turned so as to have its bore communicate with the evaouatedinterior of the vessel so that now the electron stream passing throughthe opening 54 strikes the object. The objective coil 55 is providedwith an upper cover 55. 59 designates a set of screening cylindersserving to protect the electron stream passing through the innercylinder from being affected by outer magnetic fields.

To select the portion of the object to be magnied, the sluice body 20containing the object can be moved in any direction transversely to thepath of the magnifying electron beam and relatively to the stationarypart 26 containing the objective coil 55. The adjustment is efiected byadjusting screws 60 which may be turned in the holders 6| so as to movein the upward and downward direction. This adjusting movement of eachscrew 63 is transmitted to a pressure body 53 firmly secured to thesluicing device 20 by means of a lever 52. 64 denotes a resilient holderopposite to the pressure body 63.

A ring-shaped rubber disk 55 serves to seal the circular opening betweenthe relatively movable parts 20 and 55. The outer periphery of diso 65is pressed by a pressure ring 65 against the plate 55 and its innerperiphery by a pressure ring 67 against a circular fiange 63 of thesluicing device 20. To rmly press the pressure rings 65 and 67 twocorrespondingly threaded rings 69, 'ID are employed. The ring 69 isprovided with an inner thread which is screwed on a oorresponding threadof the sluicing deVioe 2%). The ring TO has an outer thread which isscrewed in a corresponding thread of the plate 56. The circularinterstice between the two pressure rings 66 and 6'! enables the sluicesection 20 to move in a transverse direction relatively to the objectivecoil 55 without interfering with the vacuum in the microscope vessel.The flange 68 has a trapezoidal cross-section which ts in acorrespondingly shaped trapezoidal indentation 'H of the plate 56 withsufficient clearance.

In order that the observer when seated may easily efiect the fineadjustment of the arrangement during the operation of the microscope,rodshaped or tubular attachments 73 extending in the downward directionare secured to the adjusting screws 65. These extensions are provided attheir lower end with knobs '15, respectively, and at the upper end withknobs 14, respectively. By turning the knobs '55, the observer whenseated causes the object to be displacecl in. a transverse directionrelatively to the parts of the electronic microscope placed below theobject. The upper adjusting knobs 'M permit making correspondingadjustments when the observer stands and cbserves the intermediate imagethrough the inspection windows 33.

What is claimed is:

1. In an electronic microscope, a tubular vacuum vessel subdividedtransversely with respect to its longitudinal axis so as to form aplurality of consecutive wall sections surrounding said axis, twoconsecutive and adjoining vessel sections having scaling conesconcentric to said axis and engaging each other to form a rigid andvacuum-tight joint, one of said sections having a screw threadconcentric to said axis, and a screw nut disposed on said thread forContacting a concentric surface of said other section when screwedagainst it in order to forcbly disengage said sealing cones.

2. In an electron microscope, a vacuum vessel subdivided transverse tothe electron-optical axis so as to form a plurality of consecutive wallsections, one of said sections having two scaling cones, one at eitherend, and the two adjoining sections having each a sealing cone engagingthe appertaining cone of the aforesaid section to form a rigid structurecomprising said three sections and two conical joints, a screw nutdisposed at each of said joints so as to ccncentrically surround thescaling cones forming the joint, said nut being scrcwed onto one of saidsections and disposed for excrting concentric prcssure on the adjoiningsection when turned so as to move against said latter section, therebyforcibly dis engaging the joint.

3. In an electron microscope having an objective lens and a projectionlens, in combination, a vacuum Vessel subdivided transversc to theelcctron-optical axis so as to form a plurality of consecutive wallsections, one of said sections carrying said objective lens, another ofsaid seotions carrying said projection lens, and a third of saidsections being arrangcd intermediate said first and second saidsections, said intermediate vessel section having two scaling cones, oneat either end, and the two adjoining sections having each a scaling coneengaging the corresponding cone of said intermediate section to form arigid structure comprising the lcns-carrying vessel sections in rigidbut separablc rclation to each other, and screw means arrangedconcentrically to said sections for forcibly disengaging said cone pairsto separate said sections from one another.

4. An electronic Vacuum device having separable Vcsscl portionsadjoining each other, one of said vessel portions having a scaling coneand the other a corrcsponding conical seat engaging said cone forrigidly joining and tightly scaling said adjoining portions, one of saidvcsscl portions having a screw thread coaxial with said scaling cone andseat, and a screw nut disposed on said thread for contacting andexerting force on said other vesscl portion when being screwed againstsaid other vessel portion so as to separate said two portions.

5. An electronic vacuum device having separate Vessel portions adjoiningeach other, one of said vcsscl portions having a scaling cone and theother a conical seat engaging said cone for rigidly joining and tightlyscaling said adjoining portions, a screw thread integral with one ofsaid adjoining parts and surrounding the axis of said cone and. seat, ascrew nut disposed on said thread for Contacting said other part whenscrewed in one direction, a ring-shaped member firmly Secured to saidother part and arranged concentrically to said nut to be contactcdthereby When the latte' is scrcwcd in the other direction, whereby saidnut serves to press said scaling cones together as well as to disengagethcm depending upon its direction of rotation.

6. An electronic vacuum vesscl having a first part consisting of ceramicmaterial and provided with a scaling cone, an adjoining second part alsohaving a scaling conc for engaging said first cone, said second partbeing provided with a screw thread concentric to its scaling cone, ascrew nut disposed on said thread, and a separate prcssurc ring firmlysecured to said ceramic part to be contacted by said nut when screwingthe lattcr towards said ceramic part.

I-IANS SCHUCHMANN. BODO VON BORRIES. HELMUT RUSKA.

